In an economy of software agents (referred to hereafter simply as “agents”), in which autonomous agents buy and sell information goods and services to each other, it is important for agents to be able to communicate with other agents (e.g., potential customers or suppliers). Generally this requires somehow discovering an address which is used to open a communication session with that agent. It may be assumed that each agent has access to at least one directory service listing addresses of other agents.
However, under the assumption that agents and agent-hosting services are owned by a multitude of owners, each of which may define conditions under which an agent is listed, the local directory service available to an agent cannot be assumed to contain listings of all agents everywhere. Furthermore, it is clearly possible that the directory service is not a part of any well-ordered hierarchy which may be exhaustively searched. Furthermore, since the population of agents and the services they offer constantly change, no static scheme of registration is feasible over any significant period of time.
Initially, the problem appears to be similar to any number of problems encountered in distributed systems, in which remote resources must be located. One familiar example of this is the problem of locating machines on the internet by name. This problem is solved using DNS, a hierarchical mapping scheme in which machine names are mapped onto IP addresses. In general, as in DNS, solutions to these problems assume a structure or regularity that the context of this invention does not permit. For example, in the context of most interest to the instant invention: (1) there is no universal hierarchy of directory services; (2) there is no centralized or hierarchically managed directory system listing all agents everywhere; and (3) directory services are under the control of independent agents, i.e., a directory service has the option of refusing to cross-list or of refusing to provide listings.
In another context so-called spiders or web-crawlers perform recursive searching over the World Wide Web (WWW) in order to locate a page that satisfies some search criteria, i.e., a page that has text or some other content that matches some specified pattern. The Web itself has the same disordered, open structure that an agent economy has, and indeed, one element of the present invention is a recursive search step. However, Web crawlers make use of recursive search to obtain, for a human user, Web pages that match some previously given search criteria, and do not enable an agent to find other agents with which the agent may interact in some way, such as buying or selling information, goods and/or services. Also, in general Web crawlers have a limited level of autonomy and decision-making capabilities.
Reference can also be had to a draft document entitled “FIPA Abstract Architecture Specification” (FIPA refers to Foundation for Intelligent Physical Agents), FIPA Document number PC00001, dated Feb. 15, 2000, in particular Section 3.2 “Directory Services”, which describes FIPA's specification of a directory service and how it functions. In this document an agent is enabled to locate agents with which to communicate by the use of an ontology (e.g., “org.fipa.ontology.stockquote”), and to retrieve from a directory service one or more directory entries for other agents that support the ontology. With regard to finding a FIPA-service, an agent, agent-platform or other FIPA-service can issue a query to a directory service to retrieve matching directory-entries, which the requesting agent can review.
Given the limitations of the prior art, there exists a need for a method whereby agents may locate one another despite the absence of any centralized directory service or of any orderly hierarchy of directory services.